Using a FFJ EA build 5_10 mount a web module with a few jar files in
web-inf/lib.  Using the Filesystem Customize dialog, see various additional
filesystems mounted automatically.  Then unmount the web module.  A significant
percentage of the time, the additional filesystems aren't unmounted
automatically. 

The reason:
WebContextObject is the data object for the root of the filesystem when it is a
web module.  WebContextObject.dispose() unmounts the additional filesystems by
using the RequestProcessor.  If no delay is given to the RequestProcessor, 
when the first filesystem is automatically removed, DataObjectPool.goOn()
returns false, and DataObjectPool.Validator.removeInvalidObject() is called
again.  Unfortunately, the fileobjects from the WebContextObject are still in
the file Set, so dispose() is called a second time (and potentially an infinite
number of times).  (Note: The dispose() method on WebInfObject also disposes
WebContextObject, so this can also set off the loop).

The workaround being considered for the web module is to set a 5-second delay
on the RequestProcessor.post() call for the automatic filesystem unmounting.